Today, containers are used for transporting load goods everywhere in the entire world. When containers should be conveyed to other continents, this preferably takes place by the containers being loaded on vessels for further transportation to the place of destination. In order for the transportation via vessel should work in safe way, it is required among other things that all containers on board have to be transportation-locked by means of some type of locking device.
Today, four container locks are placed in each corner/bottom of a container. Each lock then locks into either a subjacent container alternatively the vessel deck (if the container is farthest down in a pile). Today, up to seven (7) containers are piled on each other above deck in transportation via vessel. It means that upon unloading and loading of containers, special staff has to climb around on the container piles and lock and unlock, respectively, container corner locks manually, occasionally by means of long bars. This is both time-consuming and dangerous.
Containers are loaded and unloaded today by the fact that a crane seizes into lifting holes placed on the upper part of the container and then lifts and moves the container. In order to make the process more effective, there is a need of being able to lift more than one container simultaneously where the containers hang under each other. The containers are then connected by means of container corner locks. Today, it is primarily preferred to be able to lift two containers simultaneously—a so-called tandem lift. However, in the future, there will be a need of lifting more than two containers simultaneously.
However, there are some problems with lifting more than one container simultaneously. Firstly, it has to be ascertained that the container corner locks under the lowermost container to be lifted are loosened from subjacent points of attachment. Secondly, it has to be ascertained that all other container corner locks holding together the containers to be lifted are locked. Thirdly, it has to be ascertained that all container corner locks holding together the containers to be lifted are approved for use in a lift of one or more containers.
Locks that should be used in lifts of more than one container simultaneously are tested to verify that they withstand the load that is required. This test is then only valid during a limited period of time. This means that it has to be ascertained if all locks have been tested and when this took place.
Today, there is no better method than to manually verify the lock status of the container corner locks, and verify that each container corner lock involved in a lift of more than one container simultaneously is classified for this, as well as that the classification still is valid.